The botanical debate behind the world's most famous plant family

Gardening · Published 2 October 2026 Swipe more like this →

In short: From the bitter hops in your beer to the industrial hemp in your clothing, the Cannabaceae family is everywhere. Yet, scientists still argue over whether the plants we use are actually different species or just one highly adaptable survivor.

The Cannabaceae family, often called the hemp family, is a diverse group of roughly 170 species spread across 11 genera. While many associate it exclusively with Cannabis, the family also includes the climbing Humulus (hops) and the much larger genus Celtis, which contains about 100 species of trees. These plants vary wildly in form, ranging from the woody trees of the hackberry group to the herbaceous, erect stems of cannabis.

Taxonomy within the genus Cannabis remains a point of contention among botanists. Some researchers argue for a monotypic classification, suggesting the entire genus consists of a single, polymorphic species: Cannabis sativa. Under this view, the varieties often labeled as indica or ruderalis are merely subspecies. Others maintain a more complex view, recognizing two or three distinct species based on differences in geographic origin, branching patterns, and chemical profiles.

The distinction between hemp and marijuana is often more legal than biological. In parts of North America, the legal line is drawn at a THC concentration of 0.3 percent by dry weight. While hemp is typically grown for fiber or oilseed, marijuana varieties are selectively bred for much higher psychoactive potential, sometimes exceeding 2'5 percent THC. This chemical diversity is further manipulated by growers using selective breeding and induced parthenocarpy to target specific aromas like citrus or berry.

The evolutionary history of these plants is ancient, with fossilized pollen suggesting the family may have originated in East Asia during the Late Cretaceous, approximately 90 to 94 million years ago. While they once occupied much of the Northern Hemisphere, shifting climates eventually pushed their distribution toward more tropical regions.

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